Improvement in pans for evaporating sugar



UNITED STATES PATENT OFFICE.

SAMUEL H. GILMAN, OF NEW ORLEANS, LOUISIANA.

IVIPROVEIVIENT iN PANS FOR EVAPORATING SUGAR.

Specification forming part of Lctiers Patent No. I5.,69l. dated September 9, 1h56.i

1'0 all whom it may concern.' l

Beit known that I, SAMUEL H. GILMAN, of the city of New Orleans, in the parish of Orleans and State of Louisiana, have invented a new and useful improvement in evaporators for evaporatin g saccharine or other juices and heating water orother liquids by direct heat; and I do hereby declare the following` to be a full, clear, and exact description of the same, reference being had to the annexed drawings, which form a part of this specification, and are lettered to correspond therewith.

The object of my invention is to make an evaporator with special reference to its use in making sugar direct from cane-j uice, but Vwhich may be used for the purpose of evaporating or heating any liquids when the economy of fuel is a prominent object, and to make it economize fuel and improve the quality of the sugar to such an extent and at such'a cost for the `evaporators as'to make its `adoption a profitable investment for the smaller as well as the larger class oi' sugar-planters, and also to make it, in its construction and operation, to conform as nearly as possible to the ordinary train of sugar-kettles, with the management of which every sugar-planter is familiar.

The improvements :in the quality of sugar, when made direct from cane-juice, and the economy of fuel in makingit, have hitherto been `effected by the use of steam, which necessarily requires such expensive and complicated apparatus for its application that only the largest class of sugar-planters can adopt it and only the most skillful mechanics manage it. lThe method of making sugar on alarge majority of plantations is by the train of from four to seven hemispherical kettles set in masonry, in which they hang by flanges aroundtheir tops, with a ue under them, through which the re passes from the furnace to the chimney, the furnace being under the battery or last kettle in the train, and in which the sugar is inished, and the chimney being at the opposite end of train, near the grande 7 or irst kettle, in which the cane-juice from the mill is received, and from which, after being limed, clarified, and skimmed, it is passed into the next kettle, in which it is also skimmed, the skimmings beingthrown back into the grande, and so on until the juice reaches the battery, each kettle being skimmed back into the next, each kettle being seta few inches lower than the one preceding it, so that as they boil over the foam and skimmings will naturally run into the next kettle back, the battery being the highest and the grande the lowest kettles in the train. "7 The heatingsurface exposed to the re and hot gases in a train ofthe above description of the average size is two hundred and fifty-four square feet, and the' amountf of wood consumed to make sugar in such a train is one and one-half cords an hour, which is equivalent to one cord per hour applied to one hundred and sixty-three square feet of heating-surface. The average amount of sugar made is one thousand pounds of merchantable or drained sugar with four cords of wood weighing two thousand pounds per cord, and the amount of water eva-pd rated to obtain one pound of drained sugar being ninety-three pounds, it follows that one pound of wood evaporates butV 1.48 pound of water in the ordinary kettle-train. The proportion of wood consumed per hour to heat-` ing-surface in the best constructed steamboat and other furnaces is onecord to one thousand square feet, and the result is three and one-half pounds of water evaporated by one pound of wood, which. is a result of 2.36` to one over the kettle-train of Louisiana, and which result is obviously due to the different proportions of heating-surface to fuel. An extension of the proportion of heating-surface to fuel on the plan of the kettle-train. described for making sugar to anything like the proportions existing in other methods of applying heat to evaporate liquids is impracticable, from the nature of the eane-juice, which must be heated to the boiling-point as soon after `being expressed from the cane as is consistent with the process of clarification and skimming or otherwise cleaning, and the heated gases, after having passed under the length. of the ordinary train, are too much reduced in temperature to heat another kettle or body of juice in the required time. Y

My improvement consists ina comparatively unlimited extension of the heating surface without exposing any of the kettles or boilers which compose my train or evaporator to the exclusive low temperature of heat corresponding to the length ofthe flue from the furnace to the chimney. The temperature of the heat applied to each boiler of my evaporator corresponds to its or their direct distance from the furnace. The temperature of the heated gases after passing over the length of my evaporator being much too low to produce unaided any useful result or effect upon a body of canejuice, they are returned on the opposite side of the same thin strata of juice? increase of proportions being necessary to compensate for the decrease of temperature and make the grande and other boilers farthest from 'the furnace boil faster and more in ac-Vl cordance with the objects sought for than would bc the case with the above proportions equal. I also make such an arrangement and disposition of the cane-j uiee in vertical and horizontal strata as will, by exposing the different strata of the same-boiler to different tempcratures, produce a rapid circulation and prevent the deposit of feculent or other matv ter, and by the friction of this circulating current prevent the incrustation on the metal of t' the evaporators of lime or other substances used in clarificatiomwhich substances usually form a coating or scale on the kettles, so as to` seriously impede the passage of heat throughthe metal of which the kettles are made. This: rapid circulation also brings all parts of the body ofcane-j uice periodically into that part j of 'the evaporator which is exposed to `the greatest heat. Each one of .theboilers composing my evaporator issurrounded at its top' by a skimming-trough, for the double purpose of receiving the skimmings and to lprevent one boiler vfrom boiling over into an# other. a

Having stated the nature of my improvement -in evaporators, Iwill now proceed to de- -scribe'the manner in which the evaporator is f constructed and operated.

My evaporator is formed by a train or se` ries of open boilers of three or more, four` being here shown, Q P O N, as the best num ber, all standing in contact with and attached toeac'hother in their parts extending above: the 4heating-surface, and with a common battery, R, to finish the sugar in when a steambattery is not used `for that purpose. `Eachj boiler Q P O N, as seen onthe plan,77 is of av rectangular` form,` with a ,skimming-trough, S, .around its top. Each boiler has a flat`bot` tom, y, turning up on all sides to a common horizontal plane, N O l? Q, and then `turning horizontally outward on their sidesfto the side plates, z, and on their 'ends vlcrtically against the divisionplates z. I Each boiler has a side and bottom water-leg or strata, n o

p q', of juice, dropping perpendicularly from l legs, a o p q', meet below, and thus form the sides and bottom' of a canal, which being closed at the top by the bottom of the boiler y, from which the water-leg started, a flue, x, is thus formed entirely surrounded by juice or liquid, as seen at the sections L M, J K, G H, E E; and when the boilers are all set in one train, with their ends in contact, these vertical and horizontal strata a o p q', with the bottoms y of the boilers, forni the main central flue, x, and the vertical and horizontal strata n o p q also form the inside of the two return-fines u u and the top of the bottom return-flue c. Each boiler has one or more central waterlegs or juice-strata, a ov p q, connecting the main body of the juice above and through the bottom y with the horizontal strata a o 1J q below. These central strata divide the main lue x vertically and longitudinally into two or more divisions. The length of these central strata being less than the boiler iu which it is made, there is consequently a space 'between the ends of the central strata of each boiler (in the main flue) x which is not divided. These central strata or water-legs increase in ,number and decrease in thickness as the distance from the furnace increases, the sirup-boiler'Q next to the furnace having one and the grandeboiler N farthest from the furnace having four. The bottom plates of the boilers, y, are placed on a higher ,level as the distance from the furnace increases, and the depth of juice in .each boiler is thus kept proportionate to the temperature in the flue beneath it, while the Atop level of the-contentsof all the boilers maybe the same. The upper level of the bottoms i, which covers the side rcturn-flucs, u u, is in the same horizontal plane in all the boilers. The boilers are attached to each other by division-platesz, which plates form the ends of each boiler and the division between them.

' rlhe sidesz are also attached to and of the same height as the divisionplates, and the two connected 'form' the top of cach and all the boilers. The skimming-trough S is set on-the top of the plate z, which forms ,the top or sides of all theboilers, and the troughis made entirely around the top of each boiler, and is connected so as to make one common trough, into every part of which the skimmings from either boiler will run, and from which they can be discharged at any desired point', yor the trough may be divided and the contents discharged at .different points, at the `option of the operators.v

'The .evaporator is set in masonry, so as to form a canal for flue, u a, on each side of it, communicating with the back end of the lcentral iiue, through the evaporator, and with a bottom flue, c, below thev horizontal waterleg or strata.

racc-a j Thefurnace may be of the ordinary kinds Operetion: The train or evaporator being in operation, theA heated gases from the furnace pass into and through 'the central flue, x, to

the back end, where the current divides l and lreturns on both sides of the evaporator through the two side flues, u a, to the furnace end ofthe evaporator, where the two currents pass down and unitein the bottom fine and pass off through it to the chimney after having passed three times ,the length of the evaporator. The central strata, n op q, of juice, being in the hot-` test part of the current of heated gases, will obviously boil the most rapidly, and the current thus constantly ascending through them' must be returned through the side and bottom legs, a 0 p q', in or around which the temperature is much lower; and in this manner the desired rapid circulation is kept up, and all parts of the body of juice periodically passed up through the central legs and exj posed tothe greatest heat. Thesidc strata or legs have a temperature differing in degree on their opposite sides as they approach the furnace, where the inside has the temperature of the furnace and the outside the temperature of the gases which have passed twice the length of the evaporator; but no portion or strata of the juice in this boiler next to the furnace is exposed to a low temperature on both sides. 4 rlhe last boiler from the furnace, which is the grande, N, in which the juice is received from the juice-reservoirs, has a temperature nearly equal applied to all parts of it, as it is at the end of the central flue, m, which returns on both sides of it, and thus the even temperature (extensively diffused through the juice) which is so desirable to obtain, a goodclarification is obtained. The temperature of the hot gases in the returnflues u, a, and c would not of itself effect any useful result; but in this manner itis absorbed by the lower temperatures of the vert-ical and horizontal strata a o' p q', and acts as auxiliary to the central flue, w, or its heated contents in keeping the ebullition of the liquid under operation. The cane-juice being received in the grande N is limed and skimmed j in the usual manner of working the grande of the ordinary kettletrain, and is passed into the next kettle or boiler by the ordinary buckets or by a pump, and in the next boilerthe' The skimming-trough S may be so divided as to run its contents from the grande N, which l `v are of an inferior quality, into one reservoir,

and its contents `from the other boilers, O `l? Q, into anotherreservoir, from each of which v the clear juice may be pumped back into the grande or next boiler.

My object in extending the heating-surface `to the extentherein shown is to .reduce the temperature of the heated gases to thelowest point consistent with an adaquate draft in the chimney, and thereby, by 'transmitting their heat to the cane-juice, obtain the greatest pos sible economy of fuel.

My object in increasing the proportion of square feet .of heatingsurface to cubic contents of juice-space as the distance from the iire increases is threefold; first, to compensate for a lower temperature in the back boilers, and thereby make them boil `faster and more in accordancewith the object sought for than they otherwise would; second, to diffuse the heating-surface, as the heat decreases more extensively through the body of cane-juice in proportion as itis less clarified, and. thereby promote the separation of the feculent and other foreign matters from the juice and cause them to rise to the surface in the process of clarifying and cleaning the juice as it is received into the rst boiler, N, and advanced tothe others, respectively, as it becomes of a proper density and purity; third, to present to the action of the fire on the central legs, n, op q, athicker body or strata of juice in proportion as they approach the furnace where the heat is strongest, and thereby diminish the liability to burn the metal of which the legs are made, or to make that liability equal in all the boilers, a thicker strata' being necessary as the heat increases, to prevent the entire body of juice from being thrown out of the leg by the intense heat, and the exposed and unprotected metal thereby injured.

My object in making use of the central legs orstrata is threefold, viz: first, to produce a rapid circulation in the manner before described, and thereby preventV the deposit of foreign matters in the water-legs a o p q'aud a o p q; second, to increase the heating-surface to any required extent or proportion by the number of legs in each boiler; third, to

diffuse the heat more extensively through the j My object in making a skimming-trough,S, e

between and around the top of each boiler is to preventithe juice from being skimmed, brushed, or boiled over from one boiler into another, and thereby promote the more perfeet cleaning of ,the juice and the production of a better quality of sugar than can be made by the usual method of skimming and brushing one kettle back into another. The juice or sirup after it arrives in the battery R never or seldom requires to be skimmed. I have not shown a trough, S, around the battery K; but it may be made with one, for the purpose of receiving the sirup or sugar in case the battery boils over.

' Having stated the nature and scope of my invention, being an improvement in evaporators for the application of direct heat to the evaporation of sac'charine or other juices or Water,whatlclaim as my invention, and desire to secure by Letters Patent of the United States, is-

ll. An evaporator formed by the combination of'a train of open boilers, NO P Q, the boiler Q'to receive the first and the boiler N thelast lire, and each of the boilers in succession presenting an extent of surface to the ire in the inverse ratio of the intensity of the re, as I Well as of its (the boilers) cubic capacity, constructed and arranged substantially as described, and for the purposes specied.

2. The constructionand use of a lue, X, formed by a series of open boilers, N O P Q, and being, in a series of sections of itslength, divided longitudinally and vertically by water-legs or strata of juicev into two or more iiues or spaces, the number of flues increasing from one section to the neXt as the distance from the furnace increases, and the number of sections into which it is so divided correspond` ing to the number of boilers in the series, and each section being shorter than the boiler in which it is placed, so as to leave a space between each section where the flue X is undivided in its transverse section, substantially as described.

SAMUEL I-I. GILMAN In presence of- S. L. BUTLER, EDWIN HARRIs. 

